Del Sorbo Giuseppe Rosario, Clemens Daniel, Schneck Emanuel, Hoffmann Ingo
Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, D-14476 Potsdam, Germany.
Institut Max von Laue-Paul Langevin (ILL), 71 Avenue des Martyrs, CS 20156, F-38042 Grenoble Cedex 9, France.
Soft Matter. 2022 Mar 23;18(12):2434-2440. doi: 10.1039/d1sm01774h.
Interactions of polyelectrolytes with oppositely charged surfactants can give rise to a large variety of self-assembled structures. Some of these systems cause a drastic increase in solution viscosity, which is related to the surfactant forming aggregates interconnecting several polyelectrolyte chains. For these aggregates to form, the surfactant needs to be sufficiently hydrophobic. Here, we present a system consisting of the anionic surfactant sodium monododecyl phosphate and the cationic cellulose-based polyelectrolyte JR 400. The hydrophobicity of the surfactant can be controlled by the solution's pH. At pH > 12, the surfactant headgroup bears two charges. As a consequence, the solution viscosity decreases drastically by up to two orders of magnitude, while it can be as high as 10 Pa s at lower pH. In this paper, we investigate the changes of the mesoscopic structure of the system which lead to such drastic changes in viscosity using small angle neutron scattering and neutron spin-echo spectroscopy. Such systems are potentially interesting as they allow for a modular design where stimuli responsiveness is introduced by relatively small amounts of surfactant reusing the same simple polyelectrolyte.
聚电解质与带相反电荷的表面活性剂之间的相互作用可产生多种自组装结构。其中一些体系会导致溶液粘度急剧增加，这与表面活性剂形成连接多条聚电解质链的聚集体有关。为了形成这些聚集体，表面活性剂需要具有足够的疏水性。在此，我们展示了一个由阴离子表面活性剂磷酸单十二烷基钠和阳离子纤维素基聚电解质JR 400组成的体系。表面活性剂的疏水性可通过溶液的pH值来控制。在pH > 12时，表面活性剂头部带有两个电荷。结果，溶液粘度急剧下降多达两个数量级，而在较低pH值时其粘度可高达10 Pa·s。在本文中，我们使用小角中子散射和中子自旋回波光谱研究了导致粘度如此急剧变化的体系介观结构的变化。这类体系可能具有吸引力，因为它们允许进行模块化设计，通过相对少量的表面活性剂引入刺激响应性，同时重复使用相同的简单聚电解质。
